Anomalous density fluctuations in a strange metal

M. Mitrano, A. A. Husain, S. Vig, A. Kogar, M. S. Rak, S. I. Rubeck, J. Schmalian, B. Uchoa, J. Schneeloch, R. Zhong, G. D. Gu, P. Abbamonte

Research output: Contribution to journalArticlepeer-review

Abstract

A central mystery in high-temperature superconductivity is the origin of the so-called strange metal (i.e., the anomalous conductor from which superconductivity emerges at low temperature). Measuring the dynamic charge response of the copper oxides, χ ″(q, ω), would directly reveal the collective properties of the strange metal, but it has never been possible to measure this quantity with millielectronvolt resolution. Here, we present a measurement of χ ″(q, ω) for a cuprate, optimally doped Bi2.1Sr1.9CaCu2O8+x (Tc = 91 K), using momentum-resolved inelastic electron scattering. In the medium energy range 0.1–2 eV relevant to the strange metal, the spectra are dominated by a featureless, temperature- and momentum-independent continuum persisting to the electronvolt energy scale. This continuum displays a simple power-law form, exhibiting q2 behavior at low energy and q22 behavior at high energy. Measurements of an overdoped crystal (Tc = 50 K) showed the emergence of a gap-like feature at low temperature, indicating deviation from power law form outside the strange-metal regime. Our study suggests the strange metal exhibits a new type of charge dynamics in which excitations are local to such a degree that space and time axes are decoupled.

Original languageEnglish (US)
Pages (from-to)5392-5396
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number21
DOIs
StatePublished - May 22 2018

Keywords

  • Cuprates
  • Electron energy-loss spectroscopy
  • Non-Fermi liquid
  • Quantum criticality
  • Strange metal

ASJC Scopus subject areas

  • General

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